Dehydrating hydrated hydrosulfites.



t me" EEEEJHELNR KEY, 03? EASEL, SW'ITZEELAND, ASSIGNOH TO THE 15123111 01* SGCIETY OF CHEMIGAL INDUSTRY IN BAELE, QEBAS'EL, SWITZERLrhND.

llclillltl. No Drawing.

To all whom it may concern:

Be it knoivh that I, Hummus Rev, a citizen of the Swiss Republic, and resident of Basel, Switzerland, have invented a new Process for Dehydrating Hydrated Hydro sulfites, of which the following" is a full, clear, and exact specification.

lhe salts of hydrosulfui'ous acid which can. be obtained in form containing Water of crystallization by precipitation from their concentrated aqueous solutions by means of alcohol or otherwise, are known to be very unstable. in order that they may be converted into a. stable con'imercial form, the Water oi crystallization must be withdrawn, for Which purpose very varied. proposals have already been. made. Thus, hot alcohol or hot caustic soda lye has been used as a dehydrating agent. it is also known that" the dehydration may be effected by long heating of the precipitated salt with the mother liquor, or by heating the "Wet salt by itself or with toluene or the like, or it be dried dii ectly by placing it, in small quantities, on a previously heated plate, or by heatingthe dried hydrosullite still containing its Water of crystallization, in a vacuum or in a current of indifierent gas. To all these "methods there are objections; some are very tedious, and in others the necessary prolonged heating at a high temperature presents a danger to the success of the operation, since sodium hydrosuliite even in absence of air can decompose under certain conditions at high temperatures into thicsulfate and pyrosulfite.

According to the present invention, a sodium alcoholate, made by dissolving sodium in methyl alcohol or ethyl alcohol, may be used as a very suitable dehydratingagent for hvdrosulfites conteining Water oi crystallization.

The reaction proceeds spontaneously Without any eggiterrial application of heat, so that the dehydration can be com.- pleted in a very short time. lilereiu resides an. important. technical eliect as compared with all the processes hitherto known, since in the case ofsubstanoes so easily decom posed as hydrosulfites, the most rapid possible Working is a primary condition. of success.

The present process has nothing in common with that described in French patent specification No. 341718. Although in an example H specification to the patent of Specification of Letters Patent.

. Mar. 23?, :isii.

Application filed august 9, 1910. Serial Ho. 576,324.

additionllo. 3907 to the said French patent, a mixture of aqueous caustic soda lye with some spirit is used, this mixture behaves quite differently from anhydrous sodium ethylate. In order to obtain a dehydration by means of the said mixture, heating for a lon time at 65 C. is necessary, whereas sodium. ethylate produces the same eflect al. most instantaneously Without any Warming The process maybe practiced in dili'erent manners, and the follow-mg examples illustrate it, the parts being by we:

Example 1: 15 parts off-sodium are dis:- so-lved in 300 parts oil absolute alcohol. into the mixture of sodium ethylate and alcohol thus obtained are stirred 60 parts ofsodiuin hydrosulfite, containing Water of crystallh cation, inthe form eta dry powder or ot an occurs instantaneously in the mass as the hydrosuliite is introduced. The mixture is filtered at ordinary.temperature and the solid washed first with absolute alcohol, then I with absolute ether, and dried in thin layers at 40455" C. The drying operation ofthe salt thus obtained is sorapid and the salt is so stable that air need not be excluded. The yield is quantitative.

Example 2: Sodium hydrosulfite which has been precipitated by alcohol and washed with absolute alcohol, the amount of the salt corresponding with 60 parts of lfIa S OQZH U, is mixed in the form of the alcoholic magma Whichis left on the filter, with 44 parts of amorphous sodium ethylate free from alcohol, or with 104 parts ot the alcohol compound (IQELUNaQQH O the admixture is made-While stirring. Heat is developed and may be kept at low temperature by external cooling, While the crystallized salt i immediately changed into the anhyfite containing water of crystallization are stirred. with 400-500 parts of absolute methyl or ethyl alcohol, and 15 parts of sodium are introduced into this mixture While it is Y cooled. As soot. as all the sodium has disappeared, the mass is filtered end further my name this 12th day Of July 1910 in the worked up as described in Example 1. presence of two subscribing Witnesses..

What I claim is: The'process of dehydrating hydrated hy- 3 HERMANN' 5 drosulfites, which consists in treating hy- VVitnesses:

drated hydrosulfites with sodium aleoholate. GEO. GIFFORD,

In Witness whereof I have hereunto signed AMAND BRAUN. 

